Ioversol was disclosed as a useful nonionic x-ray contrast agent in U.S. Pat. No. 4,396,598. One intermediate used in the production of ioversol is 5-amino-N,N'-bis(2,3-diacetoxypropyl)-2,4,6-triiodoisophthalamide having the following structure: ##STR1##
Another intermediate used in the production of ioversol is 5-acetoxyacetamido-N,N'-bis(2,3-diacetoxypropyl)-2,4,6-triiodoisophthalami de having the following structure: ##STR2##
Still another intermediate used in the production of ioversol is 5-[N-(2-acetoxyethyl)acetoxyacetamido]N,N'-bis(2,3-diacetoxypropyl)-2,4,6- triiodoisophthalamide having the structure: ##STR3##
These intermediate compounds and their use in the production of ioversol are disclosed in detail in U.S. Pat. No. 4,396,598 incorporated herein by reference.
These intermediates are used in various synthetic steps to produce ioversol, a compound of the following structure: ##STR4##
The procedure used to produce ioversol heretofore used large quantities of 1,1,2-trichloroethane (TCE) as a reaction and extraction solvent for several processes in the preparation of the above-described intermediates. Due to the large quantities of TCE required in the production of ioversol and the high cost thereof, an alternative method of producing ioversol which allows for the recovery and high quality purification of TCE from the ioversol production process is desired. It is an object of the present invention to meet this need.